Fence Ledger guide
Almost no yard is flat, and the two ways of dealing with that produce different-looking fences, different material lists and different amounts of swearing.
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A fence is built from straight, square parts. The ground is neither. Everywhere the ground falls away, either the fence stops following it and a gap opens underneath, or the fence follows it and the panels stop being square. There is no third option, and every fence on a hill is one of those two choices or a mixture of them.
The two are called stepping and racking, and most people meet the distinction for the first time when a contractor asks which they want and they have no idea what is being asked.
A stepped fence keeps every panel level. Each one sits a little lower than the last, so the top of the fence descends in a staircase and the bottom does too. Where the ground drops within a panel, a triangular gap opens beneath it.
This is the easier build by a distance. Panels stay rectangular, rails stay level, pickets are all the same length, and if you are using prefabricated panels it is the only option that works at all. It also looks deliberate on a gentle, even slope — the steps read as a design decision rather than an accident.
The gap is the price. On a steep run those triangles get big enough for a determined dog to walk through, which matters if the fence exists to contain one. The usual fixes are to run a kickboard or a length of gravel board along the bottom, or to build a small retaining edge, and both are extra work that nobody remembers to price.
A racked fence keeps the bottom rail parallel to the ground the whole way. Posts stay plumb — they always do — but the rails run at the slope angle and every picket meets them at something other than ninety degrees.
The result hugs the ground with no gaps underneath, which is why it is the choice for keeping animals in. On a smooth, consistent slope it also looks better than steps.
It is considerably more work. Pickets have to be cut individually, because each one meets the ground at a different height; the tops need trimming to a consistent line or the fence looks chewed; and the offcuts are mostly waste because no two are the same. Some manufactured panels rack a few degrees by design and then refuse to go further. Board-by-board construction racks as far as you like.
Post count usually goes up. On uneven ground the spacing is measured along the slope rather than across the map, so the same boundary contains more distance than its plan length suggests, and any point where the grade changes sharply wants a post on it whether the spacing asked for one or not.
Picket waste goes up on a racked fence and stays roughly normal on a stepped one. The calculators on this site use a 10% picket allowance, which is right for flat ground and light for a racked run on a real hill. If you are racking, put the waste figure up before you order rather than discovering it halfway along.
Concrete goes up with the post count, and gate posts on a slope want more of it than gate posts on the flat, because a gate hung on sloping ground is already fighting gravity in a direction the hardware was not designed for.
You do not need instruments. Drive a stake at the top of the run and one at the bottom, tie a string between them, and level the string with a line level. Measure from the string down to the ground at the low stake: that is the fall. Measure along the string: that is the run.
Fall divided by run gives you the grade. Under about 10% almost anything works. Between 10% and 20% the choice starts to matter and racking begins to look attractive. Above that, steps become large and obvious, racking becomes real work, and it is worth asking a local contractor what people do on that street — because whatever it is, they have done it before on the same soil.
Containing an animal, or a smooth even grade: rack it. Gentle or irregular ground, prefabricated panels, or doing it yourself for the first time: step it.
The one combination to avoid is racking with panels that were not designed to rack. They will go a few degrees, resist, and then either the fixings pull or the panel twists — and it will not be obvious which has happened until a season later.